The manufacture of closures for containers generally involves thermoplastic injection molding of the sealing cap hinged together with the annular bottle mouth or container closure body in a single open part.
When plastic bottles or containers are filled, the contents are usually sealed with a tamper evident film over the open end and a closure is attached to threads or a snap locking ridge on the bottle neck over the opening. The closure must first be closed before being feed to the filling and capping machine where the closure is attached to the bottle or container by turning or press fitting.
Injection molded plastic closures with hinged caps and closure bodies are shown in U.S. Pat. Nos. 7,322,493 and 7,731,042, for example, an need not be explained in detail herein.
In some instances, the process of stripping the plastic closures from the injection mold can include rotation of the hinged cap to a closed position on the closure body, as shown for example by www.onemold.com at http://www.youtube.com/watch?v=QSgoXar3Xzc&feature=player_detailpage. For various reasons this method of closing the cap is not applicable. In some cases there is a need to cool the closure before closing the cap to avoid damage due to material or to achieve optimal mold cycle time. Further where closure bodies include nozzles or valves of different plastic materials that are installed in the closure opening in a separate step, the cap must be closed after the nozzle or valve is installed.
To close the hinged cap on the closure body specialized carousel machines are commonly used where random oriented closures are singulated in a stream of parts, then the open closures are placed from the stream into a socket in a rotating carousel, the cap is engaged with a cam or rail to rotate to a closed position, the partially closed part is transferred to another carousel with press closing tools, and compression is applied to snap the cap closed. For example see http://www.youtube.com/watch?feature=player_detailpage&v=yk GerA-zi0A.
However the conventional machinery for closing hinged caps is limited to a narrow range of sizes and shapes that can be efficiently handled. In general if a different sized closure or cap is required, the singulation, closing and compressing machinery must be modified to suit each closure. A different size or shape requires replacement of the machine parts that engage and hold the closure which involves significant expense and downtime. For this reason, closures of standard sizes and shapes are generally used to provide economies of scale in mass production. Colours can be modified by changing the plastic used for molding, however little other modification to the standard closure design is possible without extensive modification to the machinery that singulates, conveys and closes the cap on the closure body. Large quantities of identical closures are manufactured and used by packaging operators because the cost of changing the size and shape of closures is prohibitive. Smaller operators cannot compete due to the large capital costs involved. Closure designs are restricted to those standard shapes and sizes that can be manufactured and purchased at low cost.
It is desirable to provide flexibility in closure designs by allowing changes without requiring the handling, feeding and closing machinery to be extensively modified. Further it is desirable to allow packaging operators to adapt machinery rapidly so that smaller runs and custom closures can be accommodated without prohibitive costs.
Features that distinguish the present invention from the background art will be apparent from review of the disclosure, drawings and description of the invention presented below.